Salt intake and renal hemodynamics in immature and mature Dahl salt-sensitive (DS/JR) and salt-resistant (DR/JR) rats

Area of Science:

• Nephrology
• Cardiovascular Physiology
• Developmental Biology

Background:

• Hypertension development is complex, involving genetic and environmental factors.
• Renal function maturation is critical for maintaining blood pressure homeostasis.
• Dahl salt-sensitive (DS/JR) rats are a model for salt-induced hypertension.

Purpose of the Study:

• To investigate the association between abnormal renal function maturation and hypertension development in DS/JR rats.
• To assess the impact of early and chronic high salt intake on renal function and vascular response in DS/JR rats.
• To compare the effects of salt loading on DS/JR and salt-resistant (DR/JR) rats.

Main Methods:

• Studies were conducted on immature (3-week-old) and mature (8-9 weeks old) DS/JR and DR/JR rats.
• Animals were exposed to low-salt (0.15% NaCl) or high-salt (2.0% NaCl) diets during gestation and/or post-weaning.
• Physiological parameters including blood pressure (BP), glomerular filtration rate (GFR), renal blood flow (RBF), and response to acute volume expansion were measured.

Main Results:

• High-salt diet increased BP and reduced GFR and RBF in mature DS/JR rats, but not in mature DR/JR rats.
• High-salt intake in immature DS/JR rats led to poor growth, reduced GFR, and impaired RBF.
• Immature high-salt DS/JR rats failed to vasodilate during volume expansion, while immature low-salt DS/JR rats vasoconstricted.

Conclusions:

• Both mature and immature DS/JR rats exhibit abnormal responses to salt loading, indicating impaired renal function maturation.
• Early exposure to high salt significantly affects renal function maturation in DS/JR rats.
• DS/JR rats possess an enhanced vascular sensitivity to sodium during critical postnatal development periods.